Methanesulfonic Acid → Ethyl trans-2,5-dimethyl-1-piperazinecarboxylate

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Reaction Steps

Methanesulfonic acid (1.136 ml) dissolved in water (1 ml) was added to trans-2,5-dimethylpiperazine (1 g). It was cooled down in an ice bath so that the temperature did not rise above 40° C. At 25° C., EtOH (1.2 ml) was added to the mixture and the pH was adjusted to 4-5 by adding a 50% solution of potassium acetate. Finally, ethyl chloroformate dissolved in THF was added. The pH was again adjusted to 4 by adding a 50% solution of potassium acetate. The mixture was stirred for another hour at RT and evaporated off. The residue was diluted with EA, the org. phase was separated, washed with a 1M HCl solution. The aq. layers were basified with a NaOH solution till pH 10 and extracted with EA. The combined org. layers were dried (Na2SO4) and evaporated off. 740 mg of the desired compound were obtained.

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